Methods of decellularization of tissue, such as mammalian tissue, are provided, along with methods of making an extracellular matrix (ECM) preparation. Systems and apparatus useful in performing the methods are also provided.
ECM materials have found broad use in the field of regenerative medicine. A variety of methodologies for the preparation of ECM materials exist, occasionally meeting with success, as evidenced by the many commercial products available. However, there are limitations to the methods, such as ECM materials with inferior mechanics, such as failure stress and stiffness as compared to the mechanical qualities actually needed in many instances. Further, traditional methods do not necessarily work on certain tissue types and can be overly destructive to the ECM structure, resulting in ECM material that is useless or sub-optimal for a desired end use.
Tracheal defects or stenosis can result from congenital defects, trauma, or various pathologies such as cancer or infection. Partial loss of airway in a patient is debilitating and life-threatening. In pediatric patients surgical approaches including, slide tracheoplasty has been employed successfully. In adults trachea mobilization has enabled post-resection repair in some cases. Long-term stenting, dilation, and tracheostomy have been employed as palliative care in some patients. However, regardless of the approach complication rates remains very high and long term morbidity is common. There remains a cohort of patients for which standard approaches cannot be employed. Therefore, a functional tracheal replacement graft is still desirable.
Initially, engineered tracheal grafts were consisted of purified collagen sponges around a stent or synthetic scaffold (Okumura, N., et al., Experimental study on a new tracheal prosthesis made from collagen-conjugated mesh. J Thorac Cardiovasc Surg, 1994. 108(2): p. 337-45 and Teramachi, M., et al., Intrathoracic tracheal reconstruction with a collagen-conjugated prosthesis: evaluation of the efficacy of omental wrapping. J Thorac Cardiovasc Surg, 1997. 113(4): p. 701-11). Though widely used, these have had multiple deficiencies. Failure of the first engineered tracheas resulted from several causes including infection, stenosis, and complete disintegration (Wurtz, A. and E. Kipnis, Tissue-engineered airway in the clinical setting: a call for information disclosure. Clin Pharmacol Ther, 2012. 91(6): p. 973; author reply 974). Current engineered tracheas are considerably more complex and employ both multiple graft modifications and recipient treatments. Common to all is a foundation built upon a decellularized tracheal allograft or a synthetic nanofiber scaffold to provide structural support. These scaffolds are then seeded with mature airway cells or stem cells and transplanted to recipients pre-treated with growth factors (Gilbert, T. W., et al., Decellularization of tissues and organs. Biomaterials, 2006. 27(19): p. 3675-83 and Gilbert, T. W., Strategies for tissue and organ decellularization. J Cell Biochem, 2012. 113(7): p. 2217-22). Finally pedicalled island flaps are wrapped around the engineered tracheal transplant to provide a vascular source (Teramachi, M., et al., Intrathoracic tracheal reconstruction with a collagen-conjugated prosthesis: evaluation of the efficacy of omental wrapping. J Thorac Cardiovasc Surg, 1997. 113(4): p. 701-11). Considering the extreme and urgent conditions under which these engineered tracheas were transplanted, the strategy has shown modest success, arguably more so with the decellularized allografts than with the synthetic scaffolds based upon mortality rates to date. Further, despite the publication of clinical transplantation reports of the current generation of engineered tracheas, the molecular and cellular processes controlling the survival of the engineered tracheal grafts remain incompletely defined. There is a need for superior decellularized ECM material, for example, decellularized trachea materials.